pkextractimg

extract pixel values from raster image using a raster sample

SYNOPSIS

Usage: pkextractimg -i input -s sample -o output

Options: [-c class]* [-t threshold]* [-f format] [-ft fieldType] [-lt labelType] [-b band]*

Advanced options: [-sband band -eband band]* [-bndnodata band [-srcnodata value]*] [-bn attribute] [-cn attribute] [-down value]

Description

The utility pkextractimg extracts pixel values from an input raster dataset, based on the locations you provide via a sample file. The sample should be a raster dataset with categorical (integer) values. The typical use case is a land cover map that overlaps the input raster dataset. The utility then extracts pixels from the input raster for the respective land cover classes. To select a random subset of the sample raster dataset you can set the threshold option -t with a percentage value. You can provide a threshold value for each class (e.g. -t 80 -t 60). Use value 100 to select all pixels for selected class(es). As output, a new copy of the vector file is created with an extra attribute for the extracted pixel value. For each raster band in the input image, a separate attribute is created. For instance, if the raster dataset contains three bands, three attributes are created (b0, b1 and b2).

Options

• use either -short or --long options (both --long=value and --long value are supported)
• short option -h shows basic options only, long option --help shows all options

  short	long	type	default	description
  i	input	std::string		Raster input dataset containing band information
  s	sample	std::string		Raster dataset with categorical values to sample the input raster dataset. Output will contain features with input band information included
  o	output	std::string		Output sample dataset
  c	class	int		Class(es) to extract from input sample image. Leave empty to extract all valid data pixels from sample dataset
  t	threshold	float	100	Probability threshold for selecting samples (randomly). Provide probability in percentage (>0) or absolute (<0). You can provide a threshold value for each class (e.g. -t 80 -t 60). Use value 100 to select all pixels for selected class(es)
  f	f	std::string	SQLite	Output sample dataset format
  ft	ftype	std::string	Real	Field type (only Real or Integer)
  lt	ltype	std::string	Integer	Label type: In16 or String
  b	band	int		Band index(es) to extract (0 based). Leave empty to use all bands
  sband	startband	unsigned short		Start band sequence number
  eband	endband	unsigned short		End band sequence number
  bndnodata	bndnodata	int	0	Band in input image to check if pixel is valid (used for srcnodata)
  srcnodata	srcnodata	double		Invalid value(s) for input image
  bn	bname	std::string	b	For single band input data, this extra attribute name will correspond to the raster values. For multi-band input data, multiple attributes with this prefix will be added (e.g. b0, b1, b2, etc.)
  cn	cname	std::string	label	Name of the class label in the output vector dataset
  down	down	short	1	Down sampling factor

  Usage: pkextractimg -i input [-s sample] -o output

Examples

Some examples how to use pkextractimg can be found here